This invention relates generally to medical guide wires and catheters and more particularly, to guiding assemblies and guiding methods for guide wires.
Disease processes, e.g., tumors, inflammation of lymph nodes, and plaque build-up in arteries, often afflict the human body. As one specific example, atherosclerotic plaque is known to build up in the walls of arteries in the human body. Such plaque build-up restricts circulation and often causes cardiovascular problems, especially when the build-up occurs in coronary arteries.
To treat such disease, it often is necessary to guide a medical device to the diseased site, and then use the medical device to treat the diseased area. Often a guide wire is used to help guide other treatment devices. A guide wire typically is required to properly position a catheter in an artery. The guide wire is advanced and forms a path, through the artery and region of plaque build-up. The catheter or other device such as a balloon or rotational atherectomy device is then guided through the artery using the guide wire.
Known guide wires exist for the treatment of tissue. For example, known guide wires use laser energy to remove plaque build-up on artery walls as the guide wire is advanced. One known catheter includes a laser source and a guide wire body. The guide wire body has a first end and a second end, or head, and several optic fibers extend between the first end and the second end. The laser source is coupled to each of the optic fibers adjacent the catheter body first end and is configured to transmit laser energy simultaneously through the optic fibers.
To remove arterial plaque, for example, the guide wire body is positioned in the artery so that the second end of the guide wire body is adjacent a region of plaque build-up. The laser source is then energized so that laser energy travels through each of the optic fibers and substantially photoablates the plaque adjacent the second end of the catheter body. The guide wire body is then advanced through the region to photoablate the plaque in the entire region.
However, it often is difficult to guide known guide wires through the body without risking damage. For example, known guide wires typically cannot be easily advanced through partially or totally occluded arteries without substantial risk of damaging or puncturing the artery wall. As the guide wire is advanced through the artery, it will encounter obstructions to advancement including plaque build-up or the artery wall itself. However, known guide wires typically do not distinguish between plaque build-up and the artery wall. An operator may therefore incorrectly identify an obstruction as plaque build-up and attempt to push the guide wire through the obstruction, resulting in injury or puncture of the artery wall.
Arteries that become totally occluded will, over time, develop neovascular channels (microchannels) that allow blood to flow through the occlusion from the proximal side to the distal end of the lesion. These neovascular channels often offer a path of least resistance for an interventional procedure. However, known guide wire guiding methods and apparatus do not detect the presence of neovascular channels when they exist. In particular, these neovascular channels are not visible under x-ray angiography. Thus, operators of guide wires are limited in their ability to take advantage of the existence of channels in advancing the guide wire.
Accordingly, it would be desirable to provide a guide wire including a guidance system to determine the safety of advancing the guide wire further into the vessel. In particular, it would also be desirable to provide such a guide wire with the capability of providing information to an operator to distinguish among the types of obstructions which might be hindering advancement of the guide wire. It would be further desirable to detect the presence of neovascular channels through an obstruction, to identify a path from the proximal to the distal end of the obstruction.